Tantalum target materials are mainly applied in semiconductor film coating industry.
Physical vapor deposition (PVD), being one of the most essential processes in semiconductor chip production, is aimed at depositing a metal or a compound of a metal in a form of thin film onto a silicon wafer or other substrates, and finally forming complex wiring structure in semiconductor chip by cooperation of photolithography, etching and the like. PVD is completed via a sputtering machine station, and sputtering target materials are a very important and key consumptive material used in the process. Common sputtering target materials comprise highly pure tantalum, and also other nonferrous metals such as Ti, Al, Co, Cu or the like.
With increase of a wafer size from 200 mm (8 inches) to 300 mm (12 inches), the size of corresponding sputtering target material has to be increased so as to meet basic requirements of film coating by PVD. Meanwhile, when line width is decreased from 130-180 mm to 90-45 mm, the sputtering target material is changed from ultrahigh-purity Al/Ti system to ultrahigh-purity Cu/Ta system based on conductivity of a conductor and matching performance of a barrier layer. Ta target materials have increasing importance in the semiconductor sputtering industry, and demand therefore is bigger and bigger.
In prior art, tantalum target materials are mainly obtained by a process of cold rolling or cold forging. The texture components in the thickness direction of the target materials obtained are not uniform, which mainly embodies in texture (100) dominating in the upper and lower surfaces of the target materials but texture (111) dominating therebetween. Such target materials may be used on a machine station with low use requirements, but when they are used on a high-end machine station such as 12″ machine station, the inconsistent sputtering rate occurring is unacceptable.